Method and apparatus for reducing fingerprint image distortion

A fingerprint sensing apparatus, comprising:

• a light source configured produce an emitted light to illuminate a fingerprint of a user;
• a light modifier prism configured to illuminate the fingerprint with a substantially uniform light intensity using the emitted light from the light source, wherein the light modifier prism includes a curved surface configured to produce a diffused and reflected light based on the emitted light from the light source;
• the light modifier prism is further configured to direct a reflected light of the fingerprint illuminated by the diffused and reflected light;
• an image sensor configured to capture a fingerprint image from the reflected light of the fingerprint;
• a mirror and a lens in the light path between the light modifier prism and the image sensor, wherein the mirror and the lens are configured to direct the reflected light of the fingerprint image from the light modifier prism to the image sensor, and wherein
• the image sensor is configured to provide an image plane;
• the light modifier prism and the mirror are configured to provide a subject plane, wherein the subject plane is adjusted based on the light path from the light modifier prism to the image sensor, and wherein the image plane and the subject plane are extended and are configured to form an intersection;
• and
• the lens is adjusted to provide a lens plane that meets the intersection of the image plane and the subject plane;
• and
• a housing configured to hold the light source, the light modifier prism, and the image sensor within the housing.

A method for reducing fingerprint image distortion, comprising:

• producing, by a light source, an emitted light to illuminate a fingerprint of a user;
• illuminating, by a light modifier, the fingerprint with a substantially uniform light intensity using the emitted light from the light source, wherein the light modifier includes a curved surface configured to produce a diffused and reflected light based on the emitted light from the light source;
• directing, by a prism, a reflected light of the fingerprint illuminated by the diffused and reflected light from the light modifier;
• directing, by a mirror and a lens in the light path between the prism and an image sensor, the reflected light of the fingerprint image from the prism to the image sensor, wherein
• the image sensor is configured to provide an image plane;
• the prism and the mirror are configured to provide a subject plane, wherein the subject plane is adjusted based on the light path from the prism to the image sensor, and wherein the image plane and the subject plane are extended and are configured to form an intersection;
• and
• the lens is adjusted to provide a lens plane that meets the intersection of the image plane and the subject plane;
• and
• capturing, by the image sensor, a fingerprint image from the reflected light of the fingerprint.